content: /**
   * Copyright (c) 2016-present, RxJava Contributors.
   *
   * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in
   * compliance with the License. You may obtain a copy of the License at
   *
   * http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software distributed under the License is
   * distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See
   * the License for the specific language governing permissions and limitations under the License.
   */
  
  package io.reactivex.observable.internal.operators;
  
  import java.util.Collection;
  import java.util.concurrent.Callable;
  
  import io.reactivex.common.RxJavaCommonPlugins;
  import io.reactivex.common.annotations.Nullable;
  import io.reactivex.common.exceptions.Exceptions;
  import io.reactivex.common.functions.Function;
  import io.reactivex.common.internal.functions.ObjectHelper;
  import io.reactivex.observable.*;
  import io.reactivex.observable.internal.disposables.EmptyDisposable;
  import io.reactivex.observable.internal.observers.BasicFuseableObserver;
  
  public final class ObservableDistinct<T, K> extends AbstractObservableWithUpstream<T, T> {
  
      final Function<? super T, K> keySelector;
  
      final Callable<? extends Collection<? super K>> collectionSupplier;
  
      public ObservableDistinct(ObservableSource<T> source, Function<? super T, K> keySelector, Callable<? extends Collection<? super K>> collectionSupplier) {
          super(source);
          this.keySelector = keySelector;
          this.collectionSupplier = collectionSupplier;
      }
  
      @Override
      protected void subscribeActual(Observer<? super T> observer) {
          Collection<? super K> collection;
  
          try {
              collection = ObjectHelper.requireNonNull(collectionSupplier.call(), "The collectionSupplier returned a null collection. Null values are generally not allowed in 2.x operators and sources.");
          } catch (Throwable ex) {
              Exceptions.throwIfFatal(ex);
              EmptyDisposable.error(ex, observer);
              return;
          }
  
          source.subscribe(new DistinctObserver<T, K>(observer, keySelector, collection));
      }
  
      static final class DistinctObserver<T, K> extends BasicFuseableObserver<T, T> {
  
          final Collection<? super K> collection;
  
          final Function<? super T, K> keySelector;
  
          DistinctObserver(Observer<? super T> actual, Function<? super T, K> keySelector, Collection<? super K> collection) {
              super(actual);
              this.keySelector = keySelector;
              this.collection = collection;
          }
  
          @Override
          public void onNext(T value) {
              if (done) {
                  return;
              }
              if (sourceMode == NONE) {
                  K key;
                  boolean b;
  
                  try {
                      key = ObjectHelper.requireNonNull(keySelector.apply(value), "The keySelector returned a null key");
                      b = collection.add(key);
                  } catch (Throwable ex) {
                      fail(ex);
                      return;
                  }
  
                  if (b) {
                      actual.onNext(value);
                  }
              } else {
                  actual.onNext(null);
              }
          }
  
          @Override
          public void onError(Throwable e) {
              if (done) {
                  RxJavaCommonPlugins.onError(e);
              } else {
                  done = true;
                  collection.clear();
                  actual.onError(e);
              }
          }
  
          @Override
          public void onComplete() {
              if (!done) {
                  done = true;
                  collection.clear();
                  actual.onComplete();
              }
          }
  
          @Override
          public int requestFusion(int mode) {
              return transitiveBoundaryFusion(mode);
          }
  
          @Nullable
          @Override
          public T poll() throws Exception {
              for (;;) {
                  T v = qs.poll();
  
                  if (v == null || collection.add(ObjectHelper.requireNonNull(keySelector.apply(v), "The keySelector returned a null key"))) {
                      return v;
                  }
              }
          }
  
          @Override
          public void clear() {
              collection.clear();
              super.clear();
          }
      }
  }
  